Vehicles such as tractors often include powered material handling implements which are mounted directly thereon and controlled by the vehicle operator. The implement can be permanently mounted but this can restrict the vehicle to a single or limited purpose, and it is often more desirable to provide for selective attachment to maximize usage of the vehicle both with and without the implement. In addition to providing a connection between the implement and vehicle which must be both stable and secure, it is also desirable that any such attachment be convenient and easy to use.
Front end loaders traditionally have been pivoted to uprights welded or otherwise anchored to the sides of tractors, with the lift cylinders being coupled between the uprights or other structure on the tractors and the loader frame. Detachment and reattachment of loaders from such mountings has been difficult and time consuming, and has thus restricted utilization.
Selective attachment devices incorporating threaded, pinned and/or wedged arrangements have been available, however, the prior attachments have not been altogether satisfactory for one or more reasons. Many of these prior devices are connected by driving the vehicle into proper alignment and then mechanically engaging the vehicle and implement, but some devices are configured in a way that interferes with the operator's vision while maneuvering the vehicle into alignment, thus making mounting or dismounting difficult and time consuming. Another person is frequently required to let the vehicle operator know when proper alignment has been achieved. Some of the prior devices are unnecessarily complex and thus expensive, or require special tools and are thus inconvenient to use. Other problems have arisen from the particular orientation or attitude of the implement after disconnection.
U.S. Pat. No. 4,247,242 assigned to Farmhand, Inc. discloses a quick attachment device for a front end loader which overcomes some of these difficulties but still requires a wrench to effect connection and disconnection. In addition, the device in the U.S. Pat. No. 4,247,242 leaves the lift cylinders in extended condition after disconnection with the piston rods thereof exposed and subject to corrosion and, while the lift cylinders can be retracted after disconnection and extended before reconnection, this requires additional manipulative steps and time and therefore lessens convenience.
Recently issued U.S. Pat. No. 4,265,264 discloses a quick attachment device for a front end loader which requires no wrench or other tool to effect connection or disconnection. The initial and primary points of connection between the loader uprights and tractor pedestals in this device, however, are obscured from the operator's view such that guide and following surfaces and camming means must be employed to effect positive engagement. Moreover, the device in the U.S. Pat. No. 4,264,264 leaves the lift cylinders in extended condition with the piston rods thereof exposed and subject to corrosion, after dismounting the loader.
A need has thus developed for an improved quick attachment device of simplified construction whereby an implement such as a front end loader can be releasably connected to a tractor or other vehicle without additional tools, and which leaves the lift cylinders in retracted and protected positions upon disconnection.